Create a Preloader class in Actionscript 3

preloader.as

/*
* main.fla -> main.as 
*/
 
package  
{
  import flash.display.MovieClip;
	import flash.events.Event;
	/**
	 * ...
	 * @author Faisal
	 */
	public class Main extends MovieClip
	{
 
		public function Main() 
		{
 
			if (stage)
			{
				init();		
			}
			else
			{
				addEventListener(Event.ADDED_TO_STAGE, init);	
			}			
 
		}
 
 
		private function init(e:Event = null):void 
		{
			trace("I am main file loaded from Main.fla :)");			
		}
 
	}
 
}
 
 
 
/*
* preloader.fla -> preloader.as
*/
 
package  
{
	import flash.display.Loader;
	import flash.display.MovieClip;
	import flash.events.Event;
	import flash.events.ProgressEvent;
	import flash.net.URLRequest;
	/**
	 * ...
	 * @author Faisal
	 */
	public class Preloader extends MovieClip
	{
 
		public function Preloader() 
		{
			if (stage)
			{
				init();
			}
			else
			{
				addEventListener(Event.ADDED_TO_STAGE, init);
			}
 
		}
 
		private function init():void 
		{
			var url:URLRequest = new URLRequest("Main.swf");
			var myLoader:Loader = new Loader();
			myLoader.contentLoaderInfo.addEventListener(Event.COMPLETE, onLoaderComplete);
			myLoader.contentLoaderInfo.addEventListener(ProgressEvent.PROGRESS, onLoaderProgress);
 
			myLoader.load(url);
		}
 
		private function onLoaderComplete(e:Event):void 
		{
			trace(e.currentTarget.content);
			var a:MovieClip = new MovieClip();
			stage.addChild(a);
			a.addChild(e.currentTarget.content)
		}
 
		private function onLoaderProgress(e:ProgressEvent):void 
		{
			var loaded:Number = (e.bytesLoaded / e.bytesTotal) * 100;
			trace(loaded);
		}
 
	}
 
}